1. Field of the Invention
This invention relates generally to beverage dispensers, and more specifically, this invention relates to a .Iadd.method of and a .Iaddend.beverage controlling the filling of a cup to a pre-determined level.
2. Description of the Prior Art
The dispensing of beverages into a cup for immediate consumption is a long-established art. In the earlier forms of dispensers, the beverage to be consumed was discharged into a cup or other receptacle under manual control. Such an approach requires an operator to institute dispensing and to terminate dispensing. This system is acceptable in some environments, such as a soda fountain or a concession stand, but even in such environments it requires the operator to spend the time required to observe the filling of the cup. Also, there is frequently considerable spillage, and the portions of beverage will inevitably vary.
Most beverage dispensing involves the mixing of a flavor concentrate with a suitable diluent, such as soda water or plain water. There are two basic approaches to mixing the concentrate and diluent. The first is the pre-mix approach (i.e., the concentrate and diluent are mixed prior to dispensing), while this other is the post-mix approach (i.e., the concentrate and diluent are mixed during dispensing). With the advent of automatic vending machines, the need for an automatic portion control was immediately obvious. Some early beverage dispensers carried over the manual control aspect, but the problems of spillage (including deliberate wasting) and greatly variable size of portions required as automatic portion control.
The automatic portion controls that were developed, and which are still in use today, employ a measuring of the amount of pre-mixed beverage (in the pre-mix application) or the amount of concentrate and diluent (in the post-mix application) that are discharged. While this system has been generally satisfactory, there are still some problems that make automatic filling control based upon the actual product in the cup, rather than the amount of beverage to be discharged, highly desirable. Attempts to provide portion control based upon beverage in the cup, such as a weight measuring system, have not been very satisfactory.
While there may be some cases in which the portion control of current dispensers is based upon the actual volume of beverage to be discharged, most beverage dispensers now utilize solenoid valves. Accordingly, the measurement of beverage to be discharged is generally based upon actuating the solenoid valve for a given amount of time. The time is calculated to permit the valve to discharge the desired amount of beverage. However, the time calculation is based upon a given rate of flow, which assumes a given orifice size. During usage, the beverage (particularly the concentrate in a post-mix system) may well accumulate to decrease the effective orifice size, thus reducing the rate of flow and resulting in a discharge of less beverage than desired. In the case of a post-mix apparatus, not only may the portion be undesirably small, but since accumulation will normally be more of a problem with the concentrate than the diluent, the resulting beverage may also be weaker than desired.
Another difficulty is that basing portion size upon amount of beverage discharge, even if the portion control is not adversely affected by accumulation of beverage build-up in the valve, is that the dispensed portion is dependent upon the size of the cup. In other words, only a single size of cup may be utilized. However, in many locations, such as, for example, a cafeteria line, it is desirable to be able to dispense beverages in a variety of sizes of cups. Since it is usually not feasible to have a separate dispenser for each size of cup, manually controlled dispensers are still generally employed in such locations. The result, as indicated above, is spillage or waste and variation in the size of the portions. Automatic control based upon the level of liquid in a cup, regardless of the size of the cup, would be most helpful in environments such as this.